July 1590, Odawara. Toyotomi Hideyoshi's army had surrounded the Odawara Castle for over 3 months, hoping to conquer this last obstacle to his dream of the country's unification. Standing at the gate of the castle, a lone man facing the menacing guards shouted out: "Do not throw your lives away. Treasure living!". Not long after, the castle gates opened and the reigning lord surrendered. The name of that man is Kuroda Kanbee. An excellent military strategist, he worked hand-in-hand with Hideyoshi to unify the country.

Kanbee's family had fled to Harima, and were relatively poor. As the protege of Kodera Masamoto, Kanbee was very much trusted and relied upon by his lord liege. Kanbee became the head of the Kuroda clan at 22 years of age. Masamoto was aging and he very much wanted someone to take over his responsibilities, and thus he decided to marry off his much-loved daughter, Teru, to Kanbee. They were blessed with a son, but since many years had passed and yet Teru couldn't seem to conceive a second child, Kanbee decided to adopt the young children of his vassals as his proteges who were known as "Kuroda's warriors".

When Kanbee turned 30, a revolutionary young lord was slowly laying siege to all the various shogunates, aiming for a unified Japan. Harima became the place where the clash between Oda and Mori Terumoto was set. Kanbee was very attracted to Oda's unification plans, and had gone to Gifu Castle to meet up with him. There, he became acquainted with Toyotomi Hideyoshi, and soon became Hideyoshi's right-hand man, marking the birth of Gunshi Kanbee.